Cat Ba langurs are one of several langur species that are closely
associated with limestone areas meaning their habitat consists chiefly
of limestone covered Karst forest. They regularly sleep in caves
throughout the year to guard against unfavourable weather conditions. A
group of langurs may use up to twelve different caves as resting sites.
They generally spend only one or two nights in the same cave before
moving on to other feeding and resting areas. The colouration of male
and female langurs is nearly identical the only difference being a
white pubic patch on the female. Infants are a flamboyant orange and
only begin developing their adult colouration at about four months of
age.

Distribution and Ecologay of the Cat Ba Langur

The only known locality of where this langur occurs is the island of
Cat Ba. There is no evidence to suggest that the Cat Ba langur ever inhabited the
mainland. Immigration of this species onto Cat Ba Island might have
taken place long before the sea level rose due to a melting of glacial
ice. The last time this melting happened was some 10,000 years ago and
it turned the former mountainous Ha Long Bay into a huge Archipelago.

A significant proportion of a langurs’ daily life is devoted to
foraging and resting. The diet of the Cat Ba langur consists mainly of
leaves, but also includes fresh shoots, flowers, bark and some fruits
that are not palatable to human beings. Most of the langur’s food has
very high concentration of fibre and tannic acids, and often contains
substances that would be poisonous to other animals, including human
beings.

Threat Status

The World Conservation Union (IUCN) lists the Cat Ba langur as one of
the most critically endangered primate species in the world due to its
small population size and restricted range. Only about 60 langurs currently
survive in the wild. The Endangered
Primate Rescue Centre at Cuc Phuong National Park is the only facility housing captive Cat Ba langurs.

In the past, poaching constituted the primary threat to langur survival
and resulted in a population decline from an estimated 2,500-2,800
individuals in the 1960s, to a mere 53 individuals by 2000.

As a result of this steep decline in numbers, the remaining langur
population is now highly fragmented and low reproductive output
threatens their future survival. The population of the Cat Ba langur is
scattered around the island in several isolated sub-populations. Some
of these include
all-female groups with no access to males and are therefore
non-reproducing social units.
Langurs were mainly poached for the preparation of traditional
medicine, referred to as “monkey balm”, and only rarely for use as
food, as their meat has a very unpleasant smell.

The Cat Ba Langur is a member of a primate subfamily that is referred
to as leaf-eating monkeys (Colobinae), due to their food preferences(Photo Courtesy of Stefan Kobold)

A Group of Cat Ba Langurs
Like most Colobines, the Cat Ba Langur is a tree dweller and lives in
social groups with one male and several females(Photo Courtesy of Bavarian TV)